RE: How to correct wrong payables invoice rather than voiding the invoice and recreating.
Luckily, you are able to still use Returns Transaction Entry because POP doesn't know that you voided the POP Invoice match. Only AP knows this and is affected!
The "Return" type can only be used if the items are received, but not invoiced yet. "Return with Credit" lets you back out the shipment AND the invoice already entered and posted. This will "undo" for lack of a better term the quantities on the PO and let you receive against the PO again.
Make sure to check Replace Returned Goods too. This is the magic that resets the PO line quantities.
When you voided the transaction in AP, did it also back out the $10 to the 01-58050-00 account? Is there a credit showing there too?
You're going to have to reenter the invoice you voided (as just an AP transaction now) with the same amounts and GL accounts as the original invoice. The reason is by doing the return with credit, you need to apply the credit GP is going to create for the vendor to something. It would have been the original invoice entered, but that's been voided.
Then you'll be able to enter/post the shipment again, match the invoice and all the accounts will be OK.
I always tell everyone I train this: if you make a mistake (we all do), you can always fix it in the originating module and everything will roll up to the GL nicely.
I hope this helps and make sense!
Joe